Numerous methods, processes, and catalysts have been described for alkylating aromatic amines to provide valuable and useful chemical products. However, the previous suggestions have various defects including lack of selectivity of the desired product, poor conversion of the aromatic amine, and excessive deterioration of the alkylating agent which then cannot be recovered for recycle or other use.
Synthesis of products enriched in C.sub.2 -C.sub.4 alkylated primary aromatic amines by catalytic alkylation of primary aromatic amines is difficult to accomplish, especially in a one pass vapor phase reaction using a heterogeneous catalyst. For example, as shown in my prior copending application Ser. No. 618,005, in the ethylation of aniline with diethyl ether using various B-subgroup metal oxide catalysts the amount of N-ethylaniline and N,N-diethylaniline normally exceeds the amount of exclusively ring ethylated anilines, such as o-ethylaniline, p-ethylaniline, and 2,6-diethylaniline. In fact in many cases it is possible by use of the process described in that copending application to achieve extremely high selectivity to N-alkylation by using under appropriate reaction conditions such metal oxide catalysts as TiO.sub.2, ZrO.sub.2, ZnO, Ti.sub.2 O.sub.3, TiO, and the like. This is of course highly desirable and advantageous when it is desired to produce such N-alkylated products as N-ethylaniline, N,N-diethylaniline and the like. On the other hand there are situations in which it is desirable to produce a product in which the amount of exclusively ring-alkylated products exceeds the amount of product alkylated only on the nitrogen atom. One such process is described in the above copending application, and is dealt with with greater particularity herein.